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Re-Posting a modified question on java's Runtime Class

I am writing a small example to see how the javac and java commands could be implemented using the Java's Runtime class. My intension is to build a small customed IDE to compile and run Java programs. The original Message is found here...
http://www.experts-exchange.com/jsp/qManageQuestion.jsp?ta=java&qid=20307704

Some one on this board suggested the following code. The file named Top.java is the file I just want to see get compiled when the Runtime invokes the javac compiler. When I run this program, it gets compiled. I see the a .class file is getting created. But for testing purposes I purposely made a syntax error in the Top.java class and recompiled. It did not do anything. I expected the errors to be listed on the DOS shell window. I never happened. I tried may other ways. I simply cannot see the errors listing, so that I could capture them and display in a GUI interface. Could someone throw some light?
Here is the code...

class Top
{
  public void methodwitherrors()
  {
   System.out.prin();
  }
}

import java.io.*;
public class RuntimeTest
{

public static void main(String args[])
{
try{
Runtime rt = Runtime.getRuntime();

 Process p = rt.exec("d:\\j2sdk1.4.0\\bin\\javac.exe   Top.java");
 try {
 BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
 String buff = null;
 while ((buff = br.readLine()) != null) System.out.println(buff);
 br.close();
 } catch (IOException ioe) {
 System.out.println("Exception caught printing javac result");
 ioe.printStackTrace();
 }

}
catch (Exception e) {System.out.println("Exception");}
}
}
0
prain
Asked:
prain
  • 2
1 Solution
 
OviCommented:
The ideea is to read the Error stream too. There you'll get your errors. Works fine on my computer, you just need to readjust the path to javac.

import java.io.*;

public class RuntimeTest {

  public static void main(String args[]) {
    try{
      Runtime rt = Runtime.getRuntime();

      final Process p = rt.exec("/usr/lib/jdk1.4.0/bin/javac Top.java");
        new Thread(new Runnable() {
       public void run() {
            try {
              BufferedReader br_in = new BufferedReader(new InputStreamReader(p.getInputStream()));
              String buff = null;
              while ((buff = br_in.readLine()) != null) {
             System.out.println("Process out :" + buff);
             try {Thread.sleep(100); } catch(Exception e) {}
           }
              br_in.close();
            } catch (IOException ioe) {
              System.out.println("Exception caught printing javac result");
              ioe.printStackTrace();
            }
       }
     }).start();

        new Thread(new Runnable() {
       public void run() {
            try {
              BufferedReader br_err = new BufferedReader(new InputStreamReader(p.getErrorStream()));
              String buff = null;
              while ((buff = br_err.readLine()) != null) {
                   System.out.println("Process err :" + buff);
             try {Thread.sleep(100); } catch(Exception e) {}
           }
              br_err.close();
            } catch (IOException ioe) {
              System.out.println("Exception caught printing javac result");
              ioe.printStackTrace();
            }
       }
     }).start();
    } catch (Exception e) {
      System.out.println("Exception");
      e.printStackTrace();
    }
  }
}
0
 
OviCommented:
What are you doing prain ?
0
 
prainAuthor Commented:
Sorry, was late.
Good Ans.
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